<html>
<meta charset="utf-8">

<head>
    <script src="jquery-3.2.1.min.js"></script>
    <script>
        function show_msg() {
             $('#dv_show').toggle();
        }
    </script>
</head>
<div>
    <button id="btn_show" type="button" onclick="show_msg()">submit</button>
    <div id="dv_show">
        test content
    </div>
</div>

</html>